1. Field of the Invention
The present invention relates generally to Session Initiation Protocol (SIP) technology, and in particular, to a method for transmitting System Messages to various SIP based service subscribers such as Instant Messaging (IM), Push-to-Talk Over Cellular (PoC), Multimedia Messaging Service (MMS) and any other SIP based services hosted by the Service Provider.
The System Message is a special type of message transmitted by the system for different purposes (e.g., advice of charge, service notifications, warnings, instructions, etc). System Messages can contain a list of possible options and require a response from the user.
SIP is a session initiation protocol for controlling a multimedia session over Internet, including, but is not limited to, MESSAGE Method, Message Session Relay Protocol (MSRP) method, and SIP INFO Method.
2. Description of the Related Art
The MESSAGE Method, MSRP Method and SIP INFO Method will be described below.
Message Method—SIP Extension RFC 3428
The MESSAGE Method (refers to Request For Comments (RFC) 3428, “Session Initiation Protocol (SIP) Extension for Instant Messaging”, B. Campbell, Ed., et. al., RFC 3428, December 2002) sets forth the MESSAGE method, which is an extension to SIP (refers to RFC 3261, “SIP: Session Initiation Protocol”, J. Rosenberg, et. al., RFC 3261, June 2002) that allows for the transfer of Instant Messages. A MESSAGE request is an extension to SIP, thus it inherits all the request routing and security features of SIP protocol. MESSAGE requests carry the content therein in the form of Multipurpose Internet Mail Extension (MIME) body parts. MESSAGE requests do not themselves generate a SIP dialog. Ordinarily, each Instant Message stands independently, much like pager messages. MESSAGE requests can be transmitted in the dialog generated by another SIP request.
MSRP Method
Message Session Relay Protocol (MSRP) (refers to “The Message Session Relay Protocol”, B. Campbell, Ed., et. al., draft-ietf-simple-message-sessions) is a protocol for transmitting a series of related instant messages in a session. The MSRP is a text-based, connection-oriented protocol for exchanging arbitrary or binary MIME content, particularly instant messages.
SIP Info Method—RFC 2976
SIP INFO method (refers to RFC 2976, “The SIP INFO Method”, S. Donovan, RFC 2976, October 2000) allows for the carrying of session related control information that is generated during a session.
However, the transferring of system messages using the above-mentioned conventional methods only can give rise to some unexpected critical problems wherein the system messages are substantially not distinguished from normal messages, and a system message related response received from a client is not identified correctly, either. Additionally, these conventional methods have further disadvantages, in that they are precluded from waiting for a specified duration of time while a server is expecting a response from a client, and it is quite difficult for the server to provide for a user-friendly service level access control.